Tropical Storm LORENA (Text)

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TROPICAL STORM LORENA DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL EP122013
800 PM PDT THU SEP 05 2013
FOR MUCH OF THE AFTERNOON...THE CENTER OF LORENA WAS NOT WELL
DEFINED AND WAS DIFFICULT TO LOCATE. HOWEVER...TWO SSMI/S PASSES
WITHIN THE PAST 3 HOURS CLEARLY SHOW THAT A NEW CENTER HAS FORMED
FARTHER NORTH AND IS DISPLACED JUST SOUTH OF THE DEEP CONVECTION.
THE CONVECTION ITSELF WANED DURING THE PAST FEW HOURS...BUT A
RECENT BURST HAS DEVELOPED NEAR THE NEW CENTER POSITION. THE
INITIAL INTENSITY WILL BE HELD AT 35 KT BASED ON CURRENT INTENSITY
ESTIMATES OF T2.5 FROM TAFB AND SAB.
GIVEN THE REFORMATION OF THE CENTER...THE INITIAL MOTION IS SOMEWHAT
UNCERTAIN...BUT A 12-HOUR MOTION YIELDS 325/11 KT. LORENA
CONTINUES TO MOVE GENERALLY NORTHWESTWARD DUE TO A LOW- TO
MID-LEVEL RIDGE LOCATED OVER THE SOUTHERN U.S. AND NORTHERN MEXICO.
GLOBAL MODEL GUIDANCE INDICATES THAT THE MID-LEVEL VORTEX SHOULD
CONTINUE MOVING NORTHWESTWARD AROUND THE RIDGE DURING THE NEXT FEW
DAYS...BUT THE LOW-LEVEL CIRCULATION GETS LEFT BEHIND IN AN
ENVIRONMENT OF WEAK LOW-LEVEL STEERING. AS A RESULT...THE
LOW-LEVEL CENTER IS FORECAST TO SLOW DOWN CONSIDERABLY BY 36
HOURS...LINGERING NEAR THE SOUTHERN BAJA CALIFORNIA PENINSULA FOR A
COUPLE OF DAYS. THE OFFICIAL FORECAST IS A LITTLE LEFT OF THE TVCE
MULTI-MODEL CONSENSUS IN AN ATTEMPT TO DISCOUNT THE INFLUENCE OF
THE HWRF...WHICH MAINTAINS A DEEP VORTEX THAT MOVES UP THE GULF OF
CALIFORNIA.
BECAUSE THE LOW- AND MID-LEVEL CIRCULATIONS ARE EXPECTED TO
SEPARATE...LORENA WILL PROBABLY NOT BE ABLE TO STRENGTHEN MUCH
DURING THE NEXT COUPLE OF DAYS. HOWEVER...UPPER-LEVEL OUTFLOW
REMAINS GOOD AND SEA SURFACE TEMPERATURES WILL BE SUFFICIENTLY
WARM...SO THE CYCLONE IS EXPECTED TO AT LEAST MAINTAIN TROPICAL
STORM STRENGTH FOR 36 HOURS OR SO. AFTER THAT...LORENA WILL BE
INTERACTING WITH LAND...AND THE INCREASINGLY SHALLOW CIRCULATION
WILL LIKELY SPIN DOWN QUICKLY. THE UPDATED FORECAST NOW SHOWS
LORENA BECOMING A REMNANT LOW IN 3 DAYS AND DISSIPATING BY DAY 4.
THE NORTHWARD REFORMATION OF THE CENTER MEANS THAT TROPICAL STORM
FORCE WINDS COULD REACH THE SOUTHERN BAJA CALIFORNIA PENINSULA
WITHIN THE NEXT 24 HOURS OR SO...REQUIRING THE ISSUANCE OF A
TROPICAL STORM WARNING. A TROPICAL STORM WATCH HAS ALSO BEEN
ISSUED NORTH OF THE WARNING AREA ON THE WEST SIDE OF THE BAJA
CALIFORNIA PENINSULA DUE TO THE POSSIBILITY OF TROPICAL STORM FORCE
WINDS IN 36 TO 48 HOURS.
FORECAST POSITIONS AND MAX WINDS
INIT 06/0300Z 20.4N 107.6W 35 KT 40 MPH
12H 06/1200Z 21.6N 108.7W 40 KT 45 MPH
24H 07/0000Z 22.5N 109.8W 40 KT 45 MPH
36H 07/1200Z 23.2N 110.4W 35 KT 40 MPH
48H 08/0000Z 23.8N 110.6W 30 KT 35 MPH...INLAND
72H 09/0000Z 25.0N 111.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 10/0000Z...DISSIPATED
$$
FORECASTER BERG/BRENNAN
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